This invention relates to a vehicular rearview assembly. More particularly, the present invention relates to mounting of a rain sensor within a rearview mirror assembly support.
Rain sensors for detecting moisture due to rain, road splash, and the like on the outside of a vehicular windshield are conventionally mounted to the inner cabin surface of the vehicle windshield. Rain sensors typically comprise a light emitting diode, an array of light emitting diodes which are paired with a photo detector, or an array photo detectors. The rain sensor may detect moisture by sensing a change in the amount of light refracted at the outer windshield surface due to the presence or absence of moisture or use other techniques such as sending backscattering of light caused by raindrops.
Various mounting methods have been proposed with a common method including optically coupling the rain sensor detector usually to the inner cabin surface of the vehicle windshield. Rain sensor detectors are conventionally coupled to the inner cabin surface by use of an optical adhesive, or by using a removable mount, for example a mount of a type disclosed in U.S. Pat. No. 4,871,917 to O""Farrell assigned to Donnelly Corporation of Holland, Mich., the disclosure of which is incorporated by reference herein. In removable mount constructions, such as are disclosed in the Donnelly ""917 Patent, the rain sensor detection surface, which typically comprises a resilient optically clear polymer material, such as a silicone material, is mechanically pressed between the detector and the inner windshield surface by the mount.
Thus far, conventionally known means for mounting rain sensor units to vehicle windshields have several disadvantages. Optical adhesives are difficult and expensive to remove during service replacement of a damaged windshield. Furthermore, the optical adhesives, which are used to attach the rain sensors to the inner surface of the windshield, may be visible from the outside of the vehicle and, thus, can potentially detract from the vehicle appearance and styling. Moreover, the attachment of the rain sensor to the windshield either by bonding with an adhesive or by mechanical attachment often creates a noticeable obstruction of the forward field of view due to the separate and, frequently, bulky housing provided for the rain sensor unit. Furthermore, the location and bulky size of the rain sensor unit may further increase the risk of potential injury of the vehicle occupants should they impact the windshield in an accident.
In general practice, the windshield manufacturer often attaches a mirror mounting button to the windshield, for example a mounting button of the type disclosed in U.S. Pat. No. 4,930,742 assigned to Donnelly Corporation, which provides a releasable mount for the rearview mirror assembly to the windshield, the disclosure of which is incorporated in its entirety herein. When these mounting buttons are attached to the windshield, the manufacturer may need to attach a second structure, such as a mechanical guide or rail to which the rain sensor is then later attached to the vehicle, which would ultimately increase the cost of the windshield.
More recently, rain sensors have been mounted within the support arm of the interior rearview mirror assembly. These constructions utilize the teaching of the Donnelly ""917 patent as follows. Referring to FIGS. 7-9, this prior art interior rearview mirror assembly 300 includes a mirror housing 302 which supports a reflective element 304 and which is mounted to the windshield W by a support arm 306. Support arm 306 is coupled to housing 302 by a ball and socket connection 307. The rain sensor 308 is mounted inside support arm 306 and positioned to view the outside surface of windshield W. Support arm 306 includes a biasing member 309 and is adapted to releasably engage a mirror mounting button 310, which is attached to the inner surface Wxe2x80x2 of the windshield W and typically installed by the window manufacturer for coupling rearview mirror assembly 300 to the windshield (FIG. 9). In this system, mirror mounting button 310 is a ring shaped member 312 with a hollow center 314, which is glued to the inner surface of the vehicle windshield. Support arm 306 engages the outer rim of mirror mounting button 310 when the mirror assembly 300 is attached to button 310 during assembly of the vehicle at the vehicle assembly plant or during service. The rain sensor is located within the cavity of the support arm approximate the mirror mounting button and is biased into contact with the glass surface through hollow center 314 by biasing member 309. Support arm 306, however, only provides a single point of articulation for housing 302, since it must remain in a fixed position at the juncture of the support arm and the windshield in order to maintain the alignment of the sensor with the mounting button.
Although the aforementioned construction has several advantages, it has numerous disadvantages that can limit its widespread application in vehicles. By locating the rain sensor within the support arm, the support arm must necessarily include a cavity that is large enough to accommodate the rain sensor unit. Furthermore, this construction requires that the articulation of the mirror housing about the support arm be limited to a single point at the juncture of the support arm to the housing. As mentioned above, the juncture of the support arm to the mounting button must remain fixed so that rain sensor maintains contact with the inner surface of the windshield. Therefore, the present design is limited for use on single pivot mirror supports and is unsuitable for dual pivot mounting supports, which are commonly used on a wide variety of vehicles. It is also necessary to stock a special mirror design when a rain sensor is desired, which adds to inventory requirements.
Referring to U.S. Pat. Nos. 4,936,533 and 5,100,095 both assigned to Donnelly Corporation, the disclosures of which are incorporated by reference in their entireties, dual pivot mounting supports typically include a double ball joint which comprises an outer tubular support arm member with sockets formed at both ends. The sockets receive ball joints extending from the housing and mirror mounts to provide a greater range of movement for the rearview mirror assembly. Positioned in the cavity of the tubular member is a helical spring which retains the respective ball joints in the ends of the tubular support arm. Therefore, double ball joint mirrors would appear to not be well suited to accommodate a rain sensor unit within the support arm cavity.
Other considerations include vibration performance. The presence of the rain sensor in the support arm increases the weight of the rearview mirror assembly. With increased weight, potential exists for detrimental effects on the mirror assembly vibration performance. Furthermore, placement of the rain sensor in the support arm limits the choice of rearview mirror suppliers since only a limited number of mirror assembly support arm designs can accommodate such mounting of the rain sensor. Additionally, most countries have regulations that require mirror assemblies to break away upon impact in an accident. With the design illustrated in FIGS. 7-9, the choice of the mirror button design is, therefore, also limited, thus placing potential limitation on the use of these rain sensor mounts in certain countries.
Consequently, there is a need for an improved rain sensor mount for a vehicle that overcomes the above disadvantages and achieves its purpose in a manner that is economical and convenient for the automaker. Furthermore the improved rain sensor mount preferably provides broad application by allowing flexibility in the choice of design. Moreover, the improved rain sensor preferably is consistent with current safety goals and enhances the performance of the interior rearview mirror assembly.
Accordingly, the present invention provides a new and unique rain sensor mounting which is especially suitable for mounting on an inner surface of a vehicle windshield for detecting moisture on an outer surface of the windshield.
In one aspect, the invention provides a mount for mounting a rain sensor which includes a housing having an access opening on a first side or end and a port on a second side or end, preferably an opposing side or end, for positioning adjacent an inner surface of the vehicle windshield and which is adapted for mounting to a vehicle windshield. A cover is secured to the housing and covers the access opening. A mirror mounting button is provided on either the housing or the cover for mounting a rearview mirror assembly to the mount. A biasing member is supported in the housing and, preferably, is interposed between the cover and a rain sensor positioned in the housing. The biasing member urges a detecting surface of the rain sensor to project through the port and to optically couple to the vehicle windshield for detecting moisture on an outer surface of the vehicle windshield. The biasing member may comprise, for example, a helical spring, a leaf spring or a urethane disc. The biasing member may also include an internal structure of the housing that engages with the rain sensor when the housing is received on a mounting member that encompasses an opening (such as is described below) such that the detecting surface of the rain sensor is urged to project through the opening at the mounting member and intimately and, preferably, releasably contact the inner surface of the windshield, and optically couple therewith. For example, the internal cavity of the housing can comprise a resilient polymer material (such as a rubber, silicone, urethane, elastomeric (such as a thermoplastic elastomer), vinyl (such as plasticized polyvinyl chloride) or similar material with spring-like property) serving as a biasing member that urges the detecting surface of the rain sensor forward to contact the windshield when the unit is mounting in the vehicle. The biasing member may comprise a flexible polymer or a resilient gasket that compresses to urge the detecting surface of the rain sensor to contact the windshield when mounted in the vehicle.
In one form, the mirror mounting button is secured to the cover. The mirror mounting button may releasably secured to the cover or may be integrally molded with the cover to form a unitary member.
In other forms, the second side of the housing includes a layer of adhesive for mounting the housing to the vehicle windshield. For example, the adhesive may comprise a polyvinyl butyral material, an epoxy material, a urethane material, an acrylate material, an acrylic material, or a silicone adhesive material. The adhesive layer may include an opening for receiving the rain sensor whereby the detecting surface of the rain sensor can directly contact the vehicle windshield for detecting moisture on the outer surface of the windshield or the detecting surface can contact and optically couple to the cured form of said adhesive.
In yet another form, the mount includes an annular or like member having a central opening and which is adapted to mount the housing to the inner surface of the windshield. The port of the housing is aligned with the central opening of the annular member so that the rain sensor can extend through the port and through the central opening and contact the inner windshield surface for detecting moisture on an outer surface of the vehicle windshield. The housing is preferably releasably secured to the annular member so that the rain sensor can be serviced or replaced. In addition, at least the second side of the housing substantially covers and conceals the annular member.
According to another aspect of the invention, a rain sensor mount includes a housing having a cover, which covers an access opening in the housing, a means for mounting a rearview mirror assembly to the housing, and a rain sensor, which is positioned in the housing and includes a detecting surface. Furthermore, a biasing member is interposed between a portion of the housing and the rain sensor for urging the detecting surface of the rain sensor to optical couple to the windshield of the vehicle for detecting moisture on an outer surface of the windshield.
According to yet another aspect of the invention, a rearview mirror assembly is disclosed which includes a rearview mirror housing having a reflective element supported therein, a support arm mounted to the rearview mirror housing that terminates in a button attaching mirror mount, and a rain sensor module. The rain sensor module includes a rain sensor module housing having a first side or end and a second side or end, with the second side preferably including a port. The second side is positioned adjacent an inner surface of the vehicle windshield and is adapted to mount the rain sensor module housing to the vehicle windshield. The rain sensor module housing preferably also includes a cover, which covers an access opening provide in the rain sensor module housing and a rain sensor which is supported in the rain sensor module housing. Alternately, the rain sensor module may be a unitary member or construction wherein the rain sensor is housed, preferably resiliently housed, within the cavity of the housing such that the detecting surface of the rain sensor is positioned, and preferably urged to protrude, at the second side (end) of the housing that is opposite and opposing the first side (end). The rain sensor includes a detector surface, which preferably is extended though a port provided in the housing for optically coupling the rain sensor to the inner surface of the vehicle windshield. A mirror mount extends from the housing, for securing the support arm to the housing. Furthermore, the rain sensor module housing includes a biasing member supported therein which is interposed between a portion of the rain sensor module housing and the rain sensor for urging the detecting surface of the rain sensor to optically couple the rain sensor to the vehicle windshield for detecting moisture on an outer surface of the vehicle windshield. The rain sensor module can be provided in a variety of constructions, thus providing economic, convenience and flexibility benefits to automakers and their suppliers. For example, the housing of the rain sensor module and the mirror mount extending therefrom can be a unitary construction (such as can be formed by mechanically attaching or adhesively attaching a mirror mounting button to an already formed housing, or by attaching the mirror mounting button to the housing while the housing itself is being formed, such as by integral molding as is known in the molding arts), or the rain sensor, housing and mirror mount can be provided as a unitary construction, such as a unitary rain sensor module.
In one form, the support arm is secured to the rearview mirror housing by a ball and socket connection to permit repositioning of the reflective element. Additionally, and preferably, the support arm may be secured to the mirror mount by a second ball and socket connection to permit a greater range of motion for the rearview mirror housing and provide a greater range of positions for the reflective element.
As will be understood, the rain sensor mount of the present invention provides numerous advantages over prior known rain sensor mounting arrangements. For example, the rain sensor module can be attached by the windshield manufacturer at the time of the windshield fabrication and shipped to the automobile assembly plant where the rearview mirror assembly can be attached to the rain sensor module. Alternatively, the annular member may be attached to the windshield by the windshield manufacturer at the time of fabrication leaving the installation of the rain sensor module assembly optional. For example, windshields with the rain sensor mount pre-attached can be received at the vehicle assembly plant, and the rain sensor module can be attached, and the rearview mirror assembly also attached to the module, as the vehicle passes along the vehicle assembly line. Furthermore, the rain sensor mount can be mounted without detracting from the styling of the vehicle and, moreover, without obstructing the view of the driver of the vehicle. In addition, the rain sensor mount can be adapted to support a wide range of rearview mirror assemblies and, notably, rearview mirror assemblies with double ball joint support arms to permit a greater range of motion of the mirror assembly housing than the present rains sensor mounts permit. Thus, the present rain sensor mount affords the automobile manufacturer greater flexibility in its selection of the mirror assembly and the button mount and therefore can accommodate most markets"" regulations.
These and other objects, advantages, purposes and features of the invention will become more apparent from a study of the following description taken in conjunction with the drawings.